Method for preparing secondary aminoazoledisulfides



a ataiss lg Patented Sep 1961 We have also found that an inorganic base such as an 3,001,993 alkali metal oxide, hydroxide or carbonate; an alkaline METHOD FOR PREPARING S COND earth metal oxide, hydroxide or carbonate, as well as AMINOAZOLEDISULFIDES other aliphatic, alicyclic and heterocyclic tertiary amines Charles Malcolm Hendry and Earl Gregg Cuya' 5 can be used in place of an excess of the amine reactant gfipfg f i gg fiffigjg g f to accept the hydrogen halide as is illustrated in the fol- York lowing scheme wherein one mole of 2 -mercaptobenzo- No Drawing. Filed Aug. 28, 1958, Ser. No. 757,669 thiazole, at least one mole of morphollne, one mole of 7 Claims, (CL z 0 z43 Z-benzothrazyl-N-morpholinyl sulfide, one mole of sulfur 10 monochloride and two moles of sodium hydroxide are This invention relates to a new method for preparing allowed to react to form 2-benzothiazyl-N-morpholinyl secondary aminoazoledisulfides and more particularly perdisulfide.

\O-SH+HN/ 6+ 0-s +s,01,+2Na0H- U s s tains to the single step process for preparing substantial- The 2-mercaptoazoles conforming to the structure R- 1y pure secondary aminoazoledisulfides in high yield by SH wherein R" has the aforementioned designation which the reaction of a Z-mercaptoazole with a secondary amine, are useful in the present invention include but are not a Z-azolesulfenamide and a sulfur monohalide, limited to the 2-mercaptothiazoles such as Z-mercapto- Previously disclosed methods for the preparation of thiazole itself, 2-mercapto-4-methylthiazole, Z-mercaptocompounds of the aminoazoledisulfide type have involved 4-ethylthiazole, 2-mercapto-4-n-propylthia P- several steps and have yielded relatively impure products. t0-4-n-butylth1azole, 2-mercapto-4,5-dimethylthiazole, 2-

The secondary aminoazoledisulfides of the present inven- P Y Q, r ap -4,5-di-n-propyltion are useful in promoting the cure of rubber and they tlnazole, 2-mercapto-4,5-d1-n-butylth1azole, 4-phenyl-2- are particularly useful as delayed action and non-scorching mercaptothi -ph nyly p accelerators. Because the efficiency of the secondary 2-mercaptobenzothiazole, 4-phenyl-2-mercaptobenzothiaaminoazoledisulfides as rubber accelerators is largely de- 1 6-ph ny1-%mer p z h p pendent upon their purity, the relative simplicity and rahydrobenzothlazole, and 2-mercaptonaphthothiazole;

economy of the process of the present invention, as well the Z-mercaptooxazoles such as Z-mercaptooxazole itself, as the purity of its products, makes it all the more im- 2-mercapto-4-methyloxazole, 2-mercapto-4-ethyloxazole, portant commercially, 40 2-mercapto-4-n-propyloxazole, 2-mercap-to-4-n-butyloxa- The compounds which are embodied in this invention Z016, e P y P are the secondary aminoazoledisulfides which conform to ethyloxazole, 2-mercapto-4,S-di-n-propyloxazole, 2-merthe general formula P y 4 PhenyI-Z-mercaptooxazole,

R and 4-phenyl-5-methyloxazo1e; and the Z-mercaptoimida- H zoles such as Z-mercaptoimidazole itself, 2-mercapto-4- methylimidazole, 2-mercapto-4-ethylimidazole, Z-mercap- R to-4-n-propylimidazole, 2 mercapto-4-n-butylimidazole, wherein R and R are the same or different aliphatic, P ylimi zo1e, 2-mercapto-4,5-dialicyclic, or aralkyl groups or R and R togethe f ethyhmrdazole, 2-mercapto-4,S-di-n-propylimidazole, 2- a single chain and R" represents a member of the group mercapto-4,5-d1-n-butyhm1dazole, and 4-phenyl-5-methylconsisting of thiazoles, imidazoles, and oxazoles. imidazole and the like and others- The 2"memaptob@1110- The secondary aminoazoledisulfides of the present in- 0168 arethe m Preferred compounds for the P vention are prepared by the reaction of a Z-mercaptoazole P of fills mventlon; with a secondary amine, a 2-azolesulfenamide and a sulfur The Secondary ammes conforming to the Structure monohalide. Because hydrogen halide is generated dur- R ing the reaction, an acid acceptor is generally used. We have found that an excess of the secondary amine reactant will serve as the hydrogen halide acceptor as illustrated in the following reaction representative of the procwherein R and R have the aforementioned designations ess of this invention wherein Zmercaptobenzothiazole, which are useful in this invention include but are not morpholine, Z-benzothiazyl-N-morpholinyl sulfide and limited to the dialkyl amines such as dimethyl amine, di-

sulfur monochloride are allowed to react to form 2-benzoethyl amine, di-n-propyl amine, di-n-butyl amine, di-isos s s At least a two mole excessof morpholine is used to tie hexyl amine, di-n-heptyl amine, di-cyclohexyl amine, N- up the hydrogen chloride which forms during the course methyl butyl amine, di-n-octyl amine, N-ethyl cycloof the reaction. hexyl amine, and di-benzyl amine; and the heterocyclic secondary amines such as morpholine, thiomorpholine, N-methyl piperazine, N-ethyl piperazine, piperidine, ethyl-2-methyl piperidine and pyrrolidine. The preferred secondary amines for the purpose of this invention are the heterocyclic amines and the most preferred are morpholine and thiomorpholine. V

The 2-azoiesulfenamides useful in this invention are the compounds conforming to the'structure wherein R, R and R have the aforementioned designations including but not limited to such compounds =as -2- benzothiazyLN-morpholinyl sulfide, 2-thiazyl-N-morpholinyl sulfide, 4,5-di-methyl-Z-thiazyl-N-morpholinyl sulfide, 4-ethyl-2-thiazyl-N-thiomorpholinyl sulfide, Z-benzimidazyl-N-morpholinyl sulfide, 2-benzothiazyl-N-piperidyl sulfide, 2-benzothiazyl-N,N-dicyclohexyl sulfenamide, 2- benzothiazyl-N,N-dibenzyl sulfenarnide, 2-benzothiazyl- N,N-diisopropylsulfenamide and the like and others.

The sulfur monohalides useful in this invention include sulfur monochloride, sulfur monofiuoride, sulfur monobromide, and sulfur monoiodide. The preferred sulfur monohalide is sulfur monochloride.

The preferred process of this invention involves two general procedures. In the first procedure one mole of the 2-mercapt0az0le and at least 3 moles of the secondary amine are dissolved in aninert organic diluent and the mixture is warmed. One mole of the 2-azolesulfenamide is then added to the mixture and the temperature of the resulting mixture is maintained at from C. to about 135 C. and more preferably C. to about 110 C. and one mole of the sulfur monohalide is added slowly. The completed reaction mixture is a slurry of about'two moles of the amine hydrohalide suspended in the solution of secondary aminoazoledisulfide. The secondary amine hydrohalide can be separated by filtration or by extraction with water and the amine 'is recovered from its salt by known procedures.

In the second method one mole of Z-mercaptoazole and at least one mole of the secondary amine are dissolved in an inert organic diluent at a temperature of from about 25 C. to about 135 0., one mole of the 2-azolesulfenamide is added to the mixture followed by the slow'addition of first about M mole of the sulfur monohalide and then slowly and simultaneously about /2 mole of the sulfur monohalide and 2 moles of an aqueous solution of an inorganic base. The reaction product isin the organic layer of the resultingtwo phase system. The secondary aminoazoledisulfide is readily separated in high yield and excellent purity from the organic solution resulting from either of the above general procedures by concentration, cooling and filtration.

The inert organic diluents which are'useful in the present invention include aromatic hydrocarbons such as benzene, toluene and the xylenes; halogenated aromatic hydrocarbons such as chlorobenzene; nitrated aromatic hydrocarbons such as nitrobenzene; chlorinated aliphatic hydrocarbons such as chloroform; lower aliphatic esters such as ethyl acetate, ethyl propionate, methyl butyrate, propyl acetate, and the like; aliphatic cyclic ethers such as dioxane and tetrahydrofuran; and polar organic solvents such as dimethyl formamide. The preferred solvents are benzene, toluene and chloroform.

Although the procedures described above and in the examples disclose the use of an organic diluent such as benzene, toluene, chloroform and the like, it is to be understood that the process of this invention can be carried out in the absence of a diluent. The use of a diluent is preferred, however, because better temperature control can be maintained during the course of the reaction and also because of the higher purity and higher yield of secondary aminoazoledisulfide thus obtained.

4 The following examples are given to illustrate the process of this invention.

Example I A solution of 16.7 g. of Z-mercaptobenzothiazole, 8.7 g. of morpholine and 250 ml. of benzene is stirred and held at a temperature of 60 C. and 25.2 g. of Z-benzothiazyl-N-morpholinyl sulfide is added followed by the slow addition of 6.75 g. of sulfur monochloride while the reaction temperature is held at 50-71 C. To the resulting mixture is then added simultaneously in dropwise fashion 6.75 g. of sulfurmonochloride and a solution of 8 g. of sodium hydroxide in ml. of water while the reaction temperature is maintained at 60-70 C. The resulting mixture is heated for 20 minutes at 70 C. and the layers are separated. The benzene layer upon concentration and cooling yields 29.1 g. of Z-benzothiazyl-N-morpholinyl disulfide having a melting point of l28-l31 C. after one recrystallization from ethyl acetate. When other inorganic bases including potassium hydroxide, potassium carbonate, sodium carbonate and calcium oxide are used in place of sodium hydroxide comparable results are obtained.

Example II A solution of 16.7 g. of Z-mercaptobenzothiazole and 26.1 g. of morpholine in 250 ml. of benzene is stirred at 74 C. and 25.2 g. of 2-benzothiazyl-N-morpholinyl sulfide is added to the stirred solution followed by the slow addition of 13.5 g. of sulfur monochloride. The resulting mixture is stirred at 7274 C. for one hour and the hot slurry-is passed through a filter to remove the insoluble morpholine hydrochloride. The filtrate yields, upon concentration and cooling, 40.8 g. of white, crystalline 2- benzothiazyl-N-rnorpholinyl disulfide (M.P. l27-130 C.). When thiomorpholine is substituted for morpholine and Z-benzothiazyl-N-thiomorpholinyl sulfide is substituted for 2-benzothiazyl-N-morpholinyl sulfide in the above procedure comparable yields of 2-benzothiazyl-N- thiomorpholinyl disulfide are obtained.

Example Ill The procedure of Example II is followed with the exeeption that toluene is used as the diluent and a reaction temperature of from 96 to C. is employed. A yield of 28.7 g. of crystalline 2-benzothiazyl-N-morpholinyl disulfide is obtained from the toluene.

Example IV The procedure described in Example II is used with the exception that chloroform is used as the diluent and a reaction temperature of from 32-62 C. is employed. A yield of 33 g. of crystalline Z-benzothiazyl-N-morpholinyl disulfide is obtained from the chloroform.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. The method for preparing secondary aminothiazoledisulfides comprising reacting substantially one molar quantity of a member of the group consisting of 2-mercaptothiazole, 2-mercapto-4-methylthiazole, Z-mercapto- 4-ethylthiazole, Z-mercapto-tn propylthiazole, Z-mercap' to-4-n-butylthiazole, 2-mercapto-4,5-dimethylthiazole, 2- mercapto-4,S-diethylthiazole, 2-mercapto-4,5-di-n-propylthiazole, 2-mercapto-4,S-di-n-butylthiazole, 4-phenyl-2- mercaptothiazole, 4-phenyl-5-methyl-2-mercaptothiazole, Z-mercaptobenzothiazole, 4-phenyl-2-mercaptobenzothiazole, 6-phenyl-2-mercaptobenzothiazole, Z-mercaptotetrahydrobenzothiazole and Z-mercaptonaphthothiazole; at least one molar quantity of a secondary amine selected from the group consisting of morpholine, thiomorpholine, N-methyl piperazine, N-ethyl piperazine piperidine, 5- ethyl-2-methyl piperidine and pyrrolidine; substantially one molar quantity of a member of the group consisting of Z-benzothiazyl-N-morpholinyl sulfide, 2-tl1iazyl-N-morpholinyl sulfide,4,5-dimethyl-2-thiazyl-N-morpholinyl sulfide, 4-ethyl-2-thiazyl-Nethiomorpholinyl sulfide, Z-benzimidazyl-N-morpholinyl sulfide, 2-benzothiazyl-N-piperidyl sulfide, 2-benzothiazyl-N,N-dicyclohexyl sulfenamide, Z-benzothiazyl-N,N-dibenzylsulfenamide and Z-benzothiazyl-N,N-diisopropylsulfenasmide; and substantially one molar quantity of a sulfur monohalide at a temperature of from about 30 C. to about 120 C. in an inert organic diluent in the presence of substantially twoequivalent weight quantities of an alkali metal hydroxide for each molar quantity of said sulfur monohalide.

2. The method for preparing secondary aminothiazoledisulfides =comprising reacting substantially one molar quantity of a member of the group consisting of Z-mercaptothiazole, 2mercapto-4-methylthiazole, Z-mercapto- 4-ethylthiazole, 2-mercapto-4-n-propyl thiazole, 2-mercapto-4-n-butyl-thiazole, 2 mercapto-4,S-dimethylthiazole, 2- mercapto-4,S-diethylthiazole, 2-mercapto-4,5-di-n-propylthi-azole, 2-mercapto4,5-di-n-butylthiazole, 4-phenyl-2- mercaptothiazole, 4-phenyl-5-methyl-2-mercaptothiazole, Z-mercaptobenzothiazole, 4-phenyl-2-mercaptobenzothiazole, 6-phenyI-Z-mercaptobenzothiazole, Z-mercaptotetrahydrobenzothiazole and 2-mercaptonaphthothiazole; at least three molar quantities of a secondary amine selected from the group consisting of morpholine, thiomorpholine, N-methyl piperazine, N-ethyl piperazine, piperidine,'5- ethyl-Z-methyl piperidine and pyrrolidine; substantially one molar quantity of a member of the group consisting of Z-benzothiazyl-N-monpholinyl sulfide, 2-thiazyl-N-morpholinyl sulfide, 4,5-dimethyl-2-thiazyl-N-morpholinyl sulfide, 4-ethyl-2-thiazyl-N-thiomorpholinyl sulfide, Z-benzimidazyl-N-morpholinyl sulfide, 2-benzothiazyl-N-piperidyl sulfide, 2-benzothiazyl-N,N-dicyclohexyl sulfenamide, Z-benzothiazyl-N,N-dibenzylsulfenamide and 2-benz0thiazyl-N,N-diisopropylsulfenamide; and substantially one molar quantity of a sulfur monohalide at a temperature of from about 30 C. to about 110 C. in an inert organic diluent.

3. The method of preparing 2-benzothiazyl-N-morpholinyl diswlfide which comprises reacting substantially one mole of Z-mercaptobenzothiazole, at least 3 moles of morpholine, substantial-1y one mole of 2-benzothiazyl N-morpholinyl sulfide and substantially one mole of sulfur monochloride, two moles of said morpholine serving as a hydrogen chloride acceptor, at a temperature of from about 30 C. to about 120 C. in benzene.

4. The method for preparing Z-benzothiazyl-N-morpholinyl disulfide which comprises reacting substantially one mole of 2-mercaptobenzothiazole, at least 3 moles of morpholine, substantially one mole of 2-benzothiazyl- N-morpholinyl sulfide and substantially one mole of sulfur monochloride, two moles of said morpholine serving as a hydrogen chloride acceptor, at a temperature of from about 30 C. to about C. intoluene.

5. The method for preparing Z-benzothiazyl-N-morpholinyl disulfide which comprises reacting substantially one mole of Z-mercaptobenzothiazole, at least 3 moles of monpholine, substantially one mole of 2-benzothiazyl- N-morpholinyl sulfide and substantially one mole of sulfur monochloride, two moles of said morpholine serving as a hydrogen chloride acceptor, at a temperature of from about 30 C. to about 120 C. inchloroform.

6. The method for preparing 2-benzothiazyl-N-morpholinyl disulfide which comprises reacting substantially one mole of Z-mercaptobenzothiazole, at least 1 mole of morpholine, substantially one mole of Z-benzothiazyl- N-morpholinyl sulfide and substantially one mole of sulfur monochloride in the presence of substantially 2 moles of aqeuous sodium hydroxide at a temperature of from about 30 C. to about 120 C. in benzene.

7. The method for preparing 2-benzothiazyl-N-thi0- morpholinyl disulfide which comprises reacting substantially one mole of Z-mercaptobenzothiazole, at least 3 moles of thiomorpholine, substantially one mole of 2- benzothiazyl-N-thiomorpholinyl sulfide and substantially one mole of sulfur monochloride, two moles of said thiomorpholine serving as a hydrogen chloride acceptor, at a temperature of from about 30 C. to about 120 C. in benzene.

References Cited in the file of this patent UNITED STATES PATENTS 1,661,998 Carson Mar. 6, 1928 2,045,888 Tschunkur et al. June 30, 1936 2,259,164 'Iones' Oct. 14, 1941 2,273,321 Jones Feb. 17, 1942 2,510,894 Kleiman June 6, 1950 2,609,373 Beaver Sept. 2, 1952 2,713,053 DAmico July 12, 1955 2,730,526 Kinstler Jan. 10, 1956 2,747,005 Zerb'e et a1 May 22, 1956 2,766,236 Harmon Oct. 9, 1956 2,779,761 Kibler Ian. 29, 1957 2,816,881 Sullivan Dec. 17, 1957 2,837,519 Hardman June 3, 1958 2,840,556 Kinstler June 24, 1958 FOREIGN PATENTS 711,236 Great Britain June 30, 1954 

2. THE METHOD FOR PREPARING SECONDARY AMINOTHIAZOLEDISULFIDES COMPRISING REACTING SUBSTANTIALLY ONE MOLAR QUANTITY OF A MEMBER OF THE GROUP CONSISTING OF 2-MERCAPTOTHIAZOLE, 2-MERCAPTO-4-METHYLTHIAZOLE, 2-MERCAPTO4-ETHYLTHIAZOLE, 2-MERCAPTO-4-N-PROPYL THIAZOLE, 2-MERCAPTO-4-N-BUTYL-THIAZOLE, 2-MERCAPTO-4,5-DI-N-PROPYLMERCAPTO-4,5-DIETHYLTHIAZOLE, 2-MERCAPTO-4,5-DI-N-PROPYLTHIAZOLE, 2-MERCAPTO-4,5-DI-N-BUTYLTHIAZOLE, 4-PHENYL-2MERCAPTOTHIAZOLE, 4-PHENYL-5-METHYL-2-MERCAPTOTHIAZOLE, 2-MERCAPTOBENZOTHIAZOLE, 4-PHENYL-2MERCAPTOBENZOTHIAZOLE, 6-PHENYL-2-MERCAPTOBENZOTHIAZOLE, 2-MERCAPTOTETRAHYDROBENZOTHIAZLOE AND 2-MERCAPTONAPHTHOTHIAZLOE, AT LEAST THREE MOLAR QUANTITIES OF A SECOSNDARY AMINE SELECTED FROM THE GROUP CONSISTING OF MORPHOLINE, THIOMORPHOLINE, N-METHYL PIPERAZINE, N-ETHYL PIPERAZINE, PIPERIDINE, 5ETHYL-2-METHYL PIPERIDINE AND PYRROLIDINE, SUBSTNATIALLY ONE MOLLAR QUANTITY OF A MEMBER OF THE GROUP CONSISTING OF 2-BENZOTHIAZYL-N-MORPHOLINYL SULFIDE, 2-THIAZYL-N-MORPHOLINYL SULFIDE, 4,5-DIMETHYL-2-THIAZYL-N-MORPHOLINYL SULFIDE, 4-ETHYL-2-THIAZYL-N-THIOMORPHOLINYL SULFIDE, 2-BENZIMIDAZYL-N-MORPHOLINYL SULFIDE, 2-BENZOTHIAZYL-N-PIPERIDYL SULFIDE, 2-BENZOTHIAZYL-N,N-DICYCLOHEXYL SULFENAMIDE, 2-BENZOTHIAZYL-N,N-DIBENZYLSULFENAMIDE AND 2-BENZOTHIAZYL-N,N-DIISOPRROPYLSULFENAMIDE, AND SUBSTANTIALLY ONE MOLAR QUANTITY OF A SULFUR MONOHALIDE AT A TEMPERATURE OF FROM ABOUT 30*C. TO ABOUT 110*C. IN AN INERT ORGANIC DILUENT. 